帮忙看看这个位图操作函数是做什么的？很简单的。

[quanbaoxiao]

void CCISBitmap::DrawTransparent(CDC * pDC, int x, int y, COLORREF crColour,
int zoom)
{
COLORREF crOldBack = pDC->SetBkColor(m_crWhite);
COLORREF crOldText = pDC->SetTextColor(m_crBlack);
CDC dcImage, dcTrans;

// Create two memory dcs for the image and the mask
dcImage.CreateCompatibleDC(pDC);
dcTrans.CreateCompatibleDC(pDC);

// Select the image into the appropriate dc
CBitmap* pOldBitmapImage = dcImage.SelectObject(this);

// Create the mask bitmap
CBitmap bitmapTrans;
int nWidth = Width();
int nHeight = Height();
bitmapTrans.CreateBitmap(nWidth, nHeight, 1, 1, NULL);

// Select the mask bitmap into the appropriate dc
CBitmap* pOldBitmapTrans = dcTrans.SelectObject(&bitmapTrans);
CBitmap* pOldBitmapTrans = dcTrans.SelectObject(&bitmapTrans);

// Build mask based on transparent colour
dcImage.SetBkColor(crColour);
dcTrans.BitBlt(0, 0, nWidth, nHeight, &dcImage, 0, 0, SRCCOPY);

// Do the work - True Mask method - cool if not actual display
主要是下面的几条语句不知道是干什么的。
pDC->StretchBlt(x, y, nWidth/zoom, nHeight/zoom, &dcImage, 0, 0,
nWidth, nHeight, SRCINVERT);

pDC->StretchBlt(x, y, nWidth/zoom, nHeight/zoom, &dcTrans, 0, 0 ,
nWidth, nHeight, SRCAND);
pDC->StretchBlt(x, y, nWidth/zoom, nHeight/zoom, &dcImage, 0, 0,
nWidth, nHeight, SRCINVERT);

// Restore settings
dcImage.SelectObject(pOldBitmapImage);
dcTrans.BitBlt(0, 0, nWidth, nHeight, &dcImage, 0, 0, SRCCOPY);

// Do the work - True Mask method - cool if not actual display
主要是下面的几条语句不知道是干什么的。
pDC->StretchBlt(x, y, nWidth/zoom, nHeight/zoom, &dcImage, 0, 0,
nWidth, nHeight, SRCINVERT);

pDC->StretchBlt(x, y, nWidth/zoom, nHeight/zoom, &dcTrans, 0, 0 ,
nWidth, nHeight, SRCAND);
pDC->StretchBlt(x, y, nWidth/zoom, nHeight/zoom, &dcImage, 0, 0,
nWidth, nHeight, SRCINVERT);

// Restore settings
dcImage.SelectObject(pOldBitmapImage);
dcTrans.SelectObject(pOldBitmapTrans);
pDC->SetBkColor(crOldBack);
pDC->SetTextColor(crOldText);
}

[jack_wq]

缩放画图！

[wangweintk]

向pDC画一个透明位图，左上角顶点(x,y)，透明色ctColour，zoom为放大倍数。

StretchBlt是放缩和拷贝位图。

[quanbaoxiao]

但是当我传入的参数为
(pDC , x , y , RGB(255 , 255 , 255) , 1)
时，就是显示了正常的图片，就是和下面的函数是一样的，为什么呢？

void CCISBitmap::DrawTransparent(CDC * pDC, int x, int y, COLORREF crColour,int zoom)
{
CDC dcMem ;
dcMem.CreateCompatibleDC(pDC) ;
CBitmap *pOldBmp = dcMem.SelectObject(this) ;
BITMAP bm ;
::GetObject(this->GetSafeHandle() , sizeof(BITMAP) , &bm) ;
pDC->BitBlt(x , y , bm.bmWidth , bm.bmHeight , &dcMem , x , y , SRCCOPY) ;
dcMem.SelectObject(pOldBmp) ;
dcMem.DeleteDC() ;
}

[jack_wq]

最后一个参数是缩放倍数！

[quanbaoxiao]

这个知道，能不能详细地说说其他呢？

[quanbaoxiao]

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